Mirpur. The vaccine studies will be carried out at the field site in Mirpur, in urban Dhaka, where oral cholera, ETEC and rotavirus studies as well as amoebiasis studies are being conducted over the last 15 years . For the Dukoral vaccine, two doses will be given to the study participants, 14 days apart. In case of Vivotif, 3 doses will be administered on alternate days i.e. days 1, 3 and 5 or in two doses 28 days apart.